1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up
1. True or false: If the height of a rectangle equals the base of a parallelogram and the base of the rectangle equals the height of the parallelogram, then the rectangle and the parallelogram have the same area.
2. Find the area of a rectangle with a length of 53 in. and a width of 47 in.
True
2,491 in2

3. Which is a better deal, 3 discs for $5.00 or 4 discs for $7.00?
Problem of the Day
Which is a better deal, 3 discs for $5.00 or 4 discs for $7.00?
3/$5.00

4. Sunshine State Standards
MA.6.A.3.4 Solve problems given a formula.
Also MA.6.A.4.2, MA.6.G.4.3

5. You can divide any parallelogram into two congruent triangles
You can divide any parallelogram into two congruent triangles. So the area of each triangle is half the area of the parallelogram.

7. Additional Example 1: Finding the Area of a Triangle
Find the area of the triangle. 1 2
A = bh
Write the formula. 1 2
Substitute 20 for b and 12 for h.
A =
(20 · 12) 1 2
A =
(240)
Multiply.
A = 120
The area is 120 ft2.

8. Reading Math
An altitude of a triangle is a perpendicular segment from one vertex to the line containing the opposite side. The length of the altitude is the height.

9. Find the area of the triangle.
Check It Out: Example 1A
Find the area of the triangle.
4 cm
11 cm
A = bh
= (11 • 4)
= 22 cm 2 1 __

10. The diagram shows the floor plan for a triangular
Check It Out: Example 1B
The diagram shows the floor plan for a triangular
dining area. What is the area of the floor?
6.2 m
34.8 m
A = 1 2 bh =
( 34.8 • 6.2) = m

11. Additional Example 2: Application
The diagram shows the section of a forest being studied. What is the area of the section? 1 2
A = bh
Write the formula. 1 2
Substitute 43.9 for b. Substitute 16 for h.
A =
(43.9 • 16) 1 2
A =
(702.4)
Multiply.
A = 351.2
The area is km2.

12. What is the height of the piece of wood?.
Check It Out: Example 2A
Mitch uses the piece of wood shown as part of a skateboard ramp. Its area is 0.8 m . 2
What is the height of the piece of wood?.
A = bh;
0.8 = (2)
0.8 = h
The height is 0.8 m. h 1 2 __
2 m

13. Check It Out: Example 2B
Mitch wants his skateboard ramp to be at least 750 cm tall. Should he use this piece of wood to build the ramp? Explain.?.
Yes; the height is 0.8 m or 800 cm, which is greater than 750 cm.

15. Additional Example 3: Finding the Area of a Trapezoid
Find the area of the trapezoid. 1 2
A =
h(b1 + b2)‏
Use the formula.
A = 1 2
· 4( )‏
Substitute 4 for h, 14 for b1, and 12 for b2. 1 2
A = 1 2
· 4(26 )‏
A = 53
Multiply.
The area is 53 yd2.

16. Check It Out: Example 3A
Lisa wants to cut a hole in the shape of a trapezoid out of a piece of wood. The figure shows her plans, and each square of the grid represents 1 ft . What is the area of the remaining wood after she cuts out the hole? 2

17. Check It Out: Example 3A continued
5 × 8 = 40; _ 1
(3 + 6)3 = 13.5; 2
= 26.5 2
The remaining area is 26.5 ft .

18. Check It Out: Example 3B
The figure shows a vegetable garden that is planted with squash and carrots. To the nearest percent, how much of the vegetable garden is for squash?

19. Check It Out: Example 3B continued1 _ 2 1 _ 2 _ 9 3 _
(8 + 6)3 = 21; (6)(3) = 9; = , or about 0.43 21 7
About 43% of the vegetable garden is for squash.

20. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

21. Lesson Quiz
Find the area of each triangle. 1. 3. 2.
39.9 cm2
84 mi2
113 in2
Find the area of each trapezoid. 4.
22.5 m2

22. Lesson Quiz for Student Response Systems
1. Find the area of the triangle.
A cm2 B cm2
C cm2 D cm2

23. Lesson Quiz for Student Response Systems
2. Find the area of the triangle.
A. 124 m B. 134 m2
C. 132 m2 D. 144 m2

24. Lesson Quiz for Student Response Systems
3. Find the area of the trapezoid.
A m B m2
C m2 D m2